The ability of high-quality optical fiber to transmit large amounts of information without appreciable signal degradation is well known. As a result, optical fibers have found widespread use in many applications, such as voice and data transmission. Particularly in the private network and industrial markets, there is a continuing trend in which copper-based wiring is being replaced with fiber optic cabling for communication and sensing applications.
Optical fiber is typically supplied and installed as fiber optic cable. The term “fiber optic cable” refers to the combination of the actual optical fiber plus the structure in which it is carried and protected during and after installation. Generally, a fiber optic cable includes the optical fiber, aramid fibers or other strength members, and an outer jacket. Multiple optical fibers are often combined in a multi-fiber cable. Multi-fiber cables efficiently carry the requisite number of fibers to the point(s) of applied use, where it is then necessary to separate each individual optical fiber and terminate them with fiber optic connectors. In some circumstances, it may be desirable to separate the optical fibers in the multi-fiber cable into smaller groups of fibers (e.g., for different floors or areas of a building).
A furcation assembly serves as a means to facilitate the separation of multi-fiber cables by providing a protective housing for transitioning the individual fibers from the multi-fiber cable. Furcation (or “fan-out”) assemblies generally fall into two categories: pre-configured and field-installable. Field-installable furcation assemblies are partially configured at the factory, but final installation is completed in the field or other area of application.
Furcation assemblies are needed because individual optical fibers that are separated from the multi-fiber cable are protected only by a thin protective sheath. In many cases, for example, the individual fibers are only 250 μm bare fibers that require careful handling to avoid damage. Therefore, a furcation assembly (or “kit”) must be used to safely handle and deliver the optical fibers to furcation tubes. Furthermore, in order to prevent degradation of the connected fibers, the furcation assembly must protect the fibers from moisture, dust, and other contaminants.
An exemplary prior art furcation kit 10 is shown in FIG. 1. As can be seen, furcation kit 10 includes several common components used to separate individual fibers of a multi-fiber cable 12. In this regard, cable 12 is received in a housing comprising a top housing 14 and bottom housing 16 in which furcation is accomplished. In addition, a furcation block 18 holds a plurality of furcation tubes 20 which protect each optical fiber and give it a diameter suitable for a standard fiber optic connector. When furcation is complete, the individual optical fibers thus extend through the respective furcation tubes 20.
To use furcation kit 10, the outer jacket 24 and any strengthening member(s) of the multi-fiber cable 12 are stripped away to expose a desired length of the individual optical fibers. As is well known, each of the optical fibers typically includes an optical conductor (i.e., glass fiber) encased in a protective sheath. The protective sheath is typically an acrylate material that is bonded to the optical conductor as it is manufactured. The colors of the protective sheaths are typically those of the standard fiber marking scheme (blue, orange, green, brown, slate, white, red, black, yellow, violet, rose, and aqua). In this regard, furcation block 18 is preassembled with colored furcation tubes 20 that correspond with the color-coded protective sheaths. Individual optical fibers are inserted into a respective hole of the furcation block 18 and pushed through the furcation tube 20 that corresponds in color until the fiber exits the other end.
Once all of the optical fibers have been passed through the corresponding furcation tubes 20, the furcation block 18 and multi-fiber cable 12 are fixed in the furcation housing to prevent relative motion between the two. To accomplish this, the furcation block 18 is placed in the bottom housing 16 such that the recessed slots 32 of the furcation block 18 engage corresponding retention ridges 34 in the housing. Multi-fiber cable 12 is then placed in the channel 35 formed in the bottom housing 16 and secured by pinching the metal crimping tabs 36 onto the outer jacket 24. To complete the assembly, the top housing 14 is placed on the bottom housing 16 and the housings are pressed together until the housing clips 38 engage.
Typical furcation kits, similar to those shown in FIG. 1, have certain disadvantages. For example, in most cases, furcation kits are not designed to use furcation tubes with strength elements such as kevlar/aramid fibers. Moreover, current furcation kits are costly, and are generally difficult to use. For example, as described above, the technician typically has to crimp metal tabs over the multi-fiber cable to provide retention force. Not only does this metal crimp feature add to the cost of the product, but it is an inconsistent method of securing the multi-fiber cable and can damage the individual fibers. Also, because the retention force is not always consistent, the cable could be pulled out of the unit during installation or other handling.
In addition, the individual optical fibers are difficult to insert into the small furcation tubes because the furcation block holes are very small and the openings are difficult to see. Attempting to push the fibers into the tubes can cause damage to the fibers. Furthermore, because the optical fibers that are used in multi-fiber cables often have a color-coded protective sheath, the technician must place each optical fiber into the furcation tube matching in color—a very time-consuming process. The use of colored furcation tubes also adds to the cost of the product because they must be glued to the furcation block in a consistent pattern and the adhesive procedure must ensure that the ends of the tubes are not clogged with adhesive.
Finally, current furcation kits do not have a simple method to take the unit apart if needed. The current products also do not have a good means of stacking multiple units.
Examples of prior art furcation kits are shown in the following patents, each of which is incorporated herein by reference in its entirety for all purposes: U.S. Pat. Nos. 6,738,555; 6,389,214; and 5,381,501.
The present invention recognizes the foregoing considerations, and others, of the prior art.